Structure determination and structure-activity relationship of DOP Arelated compounds

我们已经提出，L-3，4-二羟基苯丙氨酸（DOPA），多巴胺的前体，是中枢神经系统的神经递质。然而，其特异性受体尚未确定。本研究利用麻醉大鼠血压监测系统，对DOPA识别位点的特异性配体DOPA受体进行了鉴定，并探讨了DOPA受体的构效关系。去甲肾上腺素的前体DOPA或L-threo-DOPS，当微量注射到孤束核（NTS）时，诱导降压和压力心动反应。用高效液相色谱法，我们发现了一个活性部分的多巴或DOPS的溶液，而不是多巴和DOPS本身，诱导降压和心动过缓的反应。我们分别从含有DOPA和DOPS的溶液中获得了A113和S122组分，这两种组分都具有诱导麻醉大鼠心血管反应的活性。此外，L-DOPA循环可拮抗这些反应。 关于我们 己酯（DOPA CHE）是DOPA的竞争性拮抗剂，从而表明DOPA和DOPS溶液中的一些未知活性物质通过DOPA的识别位点诱导降压和心动过缓反应。第二个项目是对线虫中的DOPA受体候选基因C06H5.7进行鉴定和结构分析。利用非洲爪蟾卵母细胞表达系统，我们确定了一个候选的G蛋白偶联受体，介导电流响应多巴C06H5.7在ASH化学感觉神经元的表达。在C06H5.7突变动物中，对未稀释苯甲醛的回避反应减弱，但对1-辛醇的回避反应未减弱。当C06H5.7在ASH神经元中外源表达时，拯救了对苯甲醛的反应性。此外，我们发现了一些水溶性的物质作为一种新的驱避剂作用于该受体的线虫。这些结果表明C06H5.7不是DOPA的受体，而是介导对挥发性和水溶性化学排斥剂的厌恶反应的第一种化学感受受体。少

We have proposed that L-3,4-dihydroxyphenylalanine (DOPA), the precursor of dopamine, is a neurotransmitter in the central nervous system. However its specific receptor(s) have not been determined yet. In this proposal, we have tried to identify specific ligands for DOPA recognistion site(s), namely DOPAreceptor(s), and investigate structure-activity relationship by using blood-pressure monitoring system in anaesthetized rats. DOPA or L-threo-DOPS, a precursor of noradrenaline, when microinjected into the nucleus tractus solitarii (NTS), induces depressor and baradycardic responses. By using HPLC, we found an active fraction of DOPA or DOPS-containing solution other than that of DOPA and DOPS itself that induced depressor and bradycardic responses. We obtained A113 and S122 fractions from DOPA and DOPS-containing solutions, respectively, both of which were active in inducing the cardiovascular responses in anaesthetized rats. In addition, these responses were antagonized by L-DOPA cycl … More ohexylester (DOPA CHE), an competitive antagonist for DOPA, thereby suggesting that some unknown active substances in DOPA and DOPS solution induced depressor and bradycardic responses through the recognition site(s) for DOPA. We are now trying further purification, identification and structural determination of these substances.The second project aimed at identification and characterization of a DOPA receptor candidate gene, C06H5.7 in C elegans. Using Xenopus laevis oocyte expression system, we identified a candidate G-protein-coupled receptor, that mediates current response to DOPA C06H5.7 was expressed in ASH chemosensory neurons. In C06H5.7 mutant animals, the avoidance response to undiluted benzaldehyde, but not to 1-octanol, was attenuated. C06H5.7, when exogenously expressed in ASH neurons, rescued the responsiveness to benzaldehyde. Furthermore, we found some water-soluble substance as a novel repellent acting on this receptor in C elegans. These results indicate that C06H5.7 is not a receptor for DOPA but the first chemosensory receptor that mediates aversive response to volatile and water soluble chemorepellents. Less